Inhibiting premature vulcanization of diene rubbers



United States Patent Ofiicc Patented Dec. 8, 1970 3,546,185 INHIBITING PREMATURE VULCANIZATION F DIENE RUBBERS Aubert Yaucher Coran, Creve Coeur, Mo., and Joseph Edward Kerwood, Saint Albans, W. Va., assignors to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Continuation-impart of applications Ser. No. 459,466, May 27, 1965; Ser. No. 549,730, May 12, 1966; and Ser. No. 579,493, Sept. 15, 1966. This application Mar. 20, 1968, Ser. No. 714,445

Int. Cl. C08f 27/06; C07d 49/34; C07g 153/00 US. Cl. 260-795 59 Claims ABSTRACT OF THE DISCLOSURE Sulfenamides characterized by carbonyl adjacent to the sulfenamide nitrogen, the characteristic nucleus of which 0 I ll RSNC where the dangling valence on the nitrogen may be linked to a second carbonyl, alkyl, aryl, cycloalkyl, hydrogen, alkylene carbon, or arylene carbon, and R is alkyl, aryl, or cycloalkyl. The compounds, many of which are new, inhibit premature vulcanization of vulcanizable elastomers and stabilize styrene-butadiene rubber.

CROSS REFERENCES TO RELATED APPLICATIONS This application is a continuation-in-part of the application Ser. No. 579,493, filed Sept. 15, 1966 now abandoned, a continuation-in-part of the application Ser. No. 549,730, filed May 12, 1966 now abandoned, and a continuation-in-part of the application Ser. No. 459,466, filed May 27, 1965 now abandoned.

BACKGROUND OF THE INVENTION This invention relates to an improved vulcanizing process for rubber and to the rubber stocks obtained by using this improved process. The invention relates to improved accelerator-inhibitor combinations for rubber. The invention also relates to new compounds useful as inhibitors of premature vulcanization in rubber. More particularly, the invention relates to a method for preventing the premature vulcanization of rubber stocks and to the rubber stocks obtained by using this method.

In the manufacture of vulcanized rubber products, crude rubber is combined with various other ingredients such as fillers, accelerators, and antidegradants to alter and improve processing of the rubber and to improve the properties of the final product. The crude rubber is put through several steps in the plant before it is ready for the final step of vulcanization. Generally the rubber is mixed with carbon black and other ingredients except the vulcanizing agent and accelerator. Then the vulcanizing and accelerating agents are added to this masterbatch in a Banbury mixer or a mill. Scorching, viz., premature vulcanization, can occur at this stage of the processing, during the storage period before vulcanizing, and during the actual vulcanization. After the vulcanizing and accelerating agents are added, the mixture of crude rubber is ready for calendering or extruding and vulcanization. If premature vulcanization occurs during the storage of the crude mixture or during processing prior to vulcanization, the processing operations cannot be carried out because the scorched rubber is rough and lumpy, consequently useless. Premature vulcanization is a major problem in the rubber industry and must be prevented in order to allow the rubber mix to be preformed and shaped before it is cured or vulcanized.

There are several reasons offered for premature vulcanization. The discovery of the thiazolesulfenamide accelerators constituted a major breakthrough in the vulcanization art because thiazolesulfenamides delayed onset of the vulcanizing process, but once it started the built-in amine activation of the thiazole resulted in strong, rapid curing. Mercaptobenzothiazole is a valuable organic vulcanization accelerator but by present standards would be considered scorchy. It has been largely replaced by the delayed-action accelerators, but further improvement has eluded the art. The development of high pH furnace blacks which lack the inherent inhibiting effect of the acidic channel blacks and the popularity of certain phenylenediamine antidegradants which promote scorching have placed increasingly stringent demands on the accelerator system.

Retarders have long been available to rubber compounders. These include N-nitrosodiphenylamine, salicyclicacid, and a terpene-resin acid blend. See Editors of Rubber World, Compounding Ingredients for Rubber, 91-94 (3rd ed., 1961). Acids as retarders are generally ineffective with thiazolesulfenamide accelerators or adversely affect this vulcanizing process. Nitrosoamines as retarders are only of limited effectiveness with thiazolesulfenamides derived from primary amines. Certain sulfenamides which are not accelerators per se have been shown to retard mercaptobenzothiazole and other scorchy accelerators, but the effect on another sulfenamide incorporated as the primary accelerator has been marginal. Similarly, mixtures of accelerating sulfenamides have been proposed as a means of improving processing safety, but neither of these innovations has significantly improved a good delayed-action accelerator.

Some of the inhibitors of the invention have vulcaniz ing and accelerating properties in their own right. For example, Belgian Patent 619,219 (1962) to US. Rubber discloses N-[(trichloromethyl)thio]maleimide as a vulcanizing agent. The sulfur-vulcanizing agents, accelerators, and antidegradants used in the combinations of this invention do not include the inhibitors of the invention. A combination of an accelerator and an inhibitor of this invention is an improved rubber additive which allows longer and safer processing time for rubber.

SUMMARY OF THE INVENTION We have discovered a class of sulfenamides which are extremely valuable inhibitors of premature vulcanization. These are characterized by the presence of a carbonyl group adjacent to the sulfenamide nitrogen. The characteristic nucleus is I ll where the dangling valence on the nitrogen may be linked to a second carbonyl, alkyl, aryl, cycloalkyl, hydrogen, alkylene carbon, or arylene carbon and R is alkyl, aryl, or cycloalkyl. Aryl is used in the usual generic sense to mean any univalent organic radical where free valence belongs to an aromatic carbocyclic nucleus and not to a side chain. The term includes radicals substituted in the carbocyclic nucleus, for example, by alkyl, alkoxy, nitro, chloro, bromo, fluoro, iodo, and hydroxy. It is preferred that the carbocyclic nucleus contain not more than one electronegative substituent. Alkyl is used in the usual generic sense to mean univalent aliphatic radicals of the series C H and includes radicals substituted in the carbon chain, as for example, by aryl, alkoxy, nitro, chloro, bromo, fluoro, iodo, and hydroxy. Primary, secondary, and tertiary alkyls are included, for example,

straight or branched chains. However, primary and secondary alkyl hydrocarbons of 1 to 20 carbon atoms are the preferred alkyl compounds of this invention. The term cycloalkyl includes cycloalkyl radicals of 5 to 12 carbon atoms in the ring. Carbon atoms of the heterocyclic nuclei which contain hydrogen can be substituted by alkyl, alkoxy, nitro, chloro, bromo, fluoro, iodo, and hydroxy, for example, 1,3 bis(phenylthio) 5-chloro-2- benzimidazolinone.

An object of this invention is to promote the progress of science and useful arts. An object of this invention is to provide a method of effectively prevent the premature vulcanization of rubber. A further object of this invention is to provide new chemical compounds useful as premature vulcanization inhibitors especially with delayedaction thiazolesulfenamides. A further object of this invention is to provide a method for a faster rate of cure for vulcanizable rubber without premature vulcanization. A further object of this invention is to provide a method to increase the available processing time prior to the actual vulcanization of rubber. A further object of this invention is to provide a method to prevent the premature vulcanization of crude rubber in storage containing a vulcanizing and accelerating agent. A further object of this invention is to provide a method to prevent the premature vulcanization of rubber during the actual vulcanization step. A further object of this invention is to prevent the premature vulcanization of rubber at any time. A further object of this invention is to'provide a safer method for processing and vulcanizing rubber. A further object of this invention is to provide a stabilizer for rubber. A further object of this invention is to provide new and improved vulcanized rubber products. A further object of this invention is to provide a vulcanized rubber stock in which the rate of reversion is reduced. Other objects of the invention will become apparent as the description of our invention proceeds. These objects are accomplished by using a sulfenamide derived from an amide or imide in the processing of rubber.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Our invention is that compounds having the formula RI-(HJNSR are excellent premature vulcanization inhibitors for a vulcanizable diene rubber Where R and R with the carbonyl and nitrogen atom constitute a radical, for example,

N-phthalimidyl,

N-succinimidyl,

N-adipimidyl,

N-glutarimidyl,

N-3 ,3-dimethylglutarimidyl,

N-hexahydrophthalimidyl,

7-oxabicyclo [2.2.1]heptane-2,3 -dicarboximid-N-yl,

7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboximid-N-yl,

tetrapropenylsuccinimid-N-yl,

me thylsuccinimid-N-yl,

octadecylsuccinimid-N-yl,

n-decenylsuccinimid-N-yl,

1,4,5 ,6,7,7-hexachlorobicyclo [2.2. 1 hep- -ene-2,3-

dicarboximid-N-yl,

5 ,5 -dimethyl-3 -hydantoinyl,

hydantoinyl,

5 ,5 -diphenyl-3-hydantoinyl,

N-maleimidyl,

4-cyclohexene-1,2-dicarboximid-N-yl,

2-benzimidazolinonl-yl,

2-benzothiazolinon-N-yl,

3-arylthio-2-benzimidazolinon-1-yl,

3-alkylthio-2-benzimidazolinon-1-yl,

3-cycloalkylthio-Z-benzimidazolinon-1-yl,

or N-(3,4,5,6-tetrahalophthalimidyl), and R" is alkyl, aryl, or cycloalkyl. More specific examples of R are CCl methyl, ethyl, propyl, isopropyl, butyl, amyl, t-butyl, phenyl, benzyl, chlorophenyl, nitrophenyl, tolyl, naphthyl, cyclooctyl, cyclopentyl, and cyclododecyl.

The premature vulcanization inhibitors of this invention include compounds of the formula I? i RC-NSR where 0 ll R-C constitutes a radical, for example, N-(arylthio)carbamoyl, N (cycloalkylthio)carbamoyl, N (alkylthio)carbamoyl, N-arylcarbamoyl, N-alkylcarbamoyl, and N-cycloalkylcarbamoyl, and R is alkyl, aryl, or cycloalkyl. More specific examples of are N- (phenylthio carbamoyl,

N- chlorophenylthio carbamoyl, N- (benzylthio carbamoyl,

N-( tolylthio) carbamoyl,

N- (methylthio carbamoyl,

N- (ethylthio carbamoyl,

N- (propylthio carbamoyl,

N- (isopropylthio carbamoyl, N- (t-butylthio carbamoyl, N-phenylcarbamoyl, N-methylcarbamoyl, N-ethylcarbamoyl, N-propylcarbarnoyl, N-isopropylcarbamoyl, N-t-butylcarb amoyl, N-trichloromethylcarb amoyl, N-benzylcarb amoyl, N-nitrophenylcarbamoyl, N-chlorophenylcarbamoyl, and N-tolylcarb amoyl,

and more specific examples of R are methyl, ethyl, propyl, isopropyl, t-butyl, trichloromethyl, phenyl, benzyl, chlorophenyl, tolyl, nitrophenyl, naphthyl, sec. butyl, n butyl, n-amyl, n-hexyl, n-heptyl, 2-ethylhexyl, n=octyl, ndecyl, n-undecyl, n-dodecyl, n-tridecyl, o-tolyl, p-tolyl, m-tolyl, p-ethylphenyl, p-isopropylphenyl, cyclooctyl, cyclopentyl, and cyclododecyl.

Examples of the new compounds of the invention are N- (cyclohexylthio phathalimide, N- cylopentylthio phthalirnide, N- (cyclododecylthio phthalimide, N- (cyclooctylthio phthalimide,

N- benzylthio) phthalimide,

9 dicarboximide, and N (trichlorornethyl)thio]succinimide.

Further examples of the compounds useful as premature vulcanization inhibitors in this invention are N- (naphthylthio) phthalimide, N- (n-butylthio) succinimide, N-(methylthio succinimide, N -(ethylthio succinimide, N-(propylthio succinimide, N- (isopropylthio succinimide, N- cyclohexylthio succinimide, and N- (cyclooctylthio succinimide; 1,3-bis (n-hexylthio -l,3-dicyclohexyl-urea, N-phenyl-N- (phenylthio urea, N-phenyl-N'- (methylthio urea, N-phenyl-N'- (ethylthio urea, N-phenyl-N- (propylthio) urea, N-phenyl-N'- (isopropylthio urea, N-phenyl-N'- (t-butylthio urea, N-phenyl-N- (n-dodecylthio urea, N-phenyl-N- (cyclohexylthio) urea, N-phenyl-N- (cyclooctylthio urea, N-methyl-N'- (phenylthio urea, N-ethyl-N- (phenylthio urea, N-propyl-N'- (phenylthio urea, N-isopropyl-N'- (phenylthio urea, N-t-butyl-N-(phenylthio) urea), N-cyclooctyl-N'- (phenylthio urea, N-cyclohexyl-N'- phenylthio urea, N-n-dodecyl-N'- (phenylthio urea, and variations thereof;

and N- (cyclododeeylthio succinimide.

Rubber stocks containing delayed-action accelerators can be used in the process of this invention. Cheaper, more scorchy accelerators can also be used with an excellent degree of improvement. The improved vulcanizing process of this invention can be used advantageously to process stocks containing furnace blacks as well as stocks containing other types of blacks and fillers used in rubber compounding. The invention is also applicable to gum stocks.

Our invention is applicable to rubber mixes containing sulfur-vulcanizing agents, peroxide-vulcanizing agents, organic accelerators for vulcanization, an antidegradants, none being the inhibitor used. For the purposes of this invention, sulfurvulcanizing agent means elemental sulfur or sulfur containing vulcanizing agent, for example, an amide disulfide or a polymeric polysulfide. The invention is applicable to vulcanization accelerators of various classes. For example, rubber mixes containing the aromatic thiazole accelerators which include benzothiazyl-2-monocyclohexyl sulfenamide, Z-mercaptobenzothiazole, N-tert-butyl-2-benzothiazole sulfenamide, 2-benzothiazolyl diethyldiehiocarbamate, and 2-(morpholinothio)benzothiazole can be used. Amine salts of mercaptobenzothiazole accelerators, for example, the t-butyl amine salt of mercaptobenzothiazole, like parts of morpholine, and 2,6-dimethyl morpholine, can be used in the invention. Thiazole accelerators other than aromatic can be used. Stocks containing accelerators, for example, the tetramethylthiuram disulfide, tetramethylthiuram monosulfide, aldehyde amine condensation products, thiocarbamylsulfenamides, thioureas, xanthates, and guanidine derivatives, are substantially improved using the process of our invention. Examples of thiocarbamylsulfenamide accelerators are shown in U.S. Pats. 2,381,392, Smith assigned to Firestone, 2,388,236, Cooper assigned to Monsanto; 2,424,921, Smith assigned to Firestone; and British Pat. 880,912, Dodson assigned to Imperial Chemical Industries Limited.

The invention is applicable to accelerator mixtures. The invention is applicable to stocks containing amine antidegradants. Rubber mixes containing antidegradants, for example, N 1,3-dimethylbutyl- -phenyl-p-phenylenediamine, N,N-bis 1,4-dimethylpentyl) -p-phenylenediamine, and other phenylenediamines, ketone, ether, and hydroxy antidegradants and mixtures thereof, are substantially improved using the process of our invention. Mixtures of antidegradants, for example, a mixture of N-1,3-dimethylbutyl-N-phenyl-p-phenylenediamine and N,N'-bis(l,4-di methylpentyl)-p-phenylenediamine, furnish a much improved final product when used with the inhibitors of this invention.

The inhibitors of our invention can be used in natural and synthetic rubbers and mixtures thereof. Synthetic rubbers that can be improved by the process of this invention include cis-4-polybutadiene, butyl rubber ethylene-propylene terpolymers, polymers of 1,3-butadiene, for example, 1,3-butadiene itself and of isoprene, copolymers of 1,3-butadiene with other monomers, for example, styrene, acrylonitrile, isobutylene, and methyl methacrylate. The invention relates to diene rubbers, and the terms rubber and diene rubber are synonymous for the purpose of this invention.

The new compound of this invention are prepared as follows:

To prepare N-(cyclohexylthio)phthalimide 23.2 grams (0.2 mole) of cyclohexylmercaptan is dissolved in 150 ml. of n-pentane, then 14.2 grams (0.2 mole) of anhydrous chlorine gas is pasesd through this solution at 0 to 5 C. over a 25 minute period. The resulting sulfenyl chloride solution is added dropwise over a thirty minute period to a solution of 29.4 grams (0.2 mole) of phthalimide and 27.0 grams (0.27 mole) of triethylamine in ml. of dimethylformamide. The reaction temperature rises from about 25 C. to about 39 C. The reaction mixture is allowed to cool. Then it is diluted with two liters of ice cold water. A white crystalline product precipitates. The yield is quantitative. The melting point of the N-(cyclohexylthio)phthalimide is 8991 C. After recrystallization of a sample of the product, the melting point is 93 -94 C. Iodometric titration of the crystallized N-(cyclohexylthio)phthalimide shows 99% purity. Analysis of the product shows 5.48% nitrogen and 12.14% sulfur. Calculated percentages for C H NO S are 5.36% nitrogen and 12.26% sulfur. The new cycloalkyl and alkyl compounds listed supra are prepared in a similar manner with comparable results.

To prepare 1,3-bis(phenylthio)-2-imidazolidinone, a solution of 8.6 grams (0.1 mole) of 2-imidazolidinone, 25.0 grams (0.25 mole) of triethylamine and 200 ml. of dimethylformamide (DMF) is cooled to 0 C. in a 500 ml. three-necked reaction flask equipped with a mechanical stirrer and thermometer. To this solution there is added 28.8 grams (0.2 mole) of benzene sulfenyl chloride dissolved in 77 ml. of CCl.; dropwise, controlling the temperature with external cooling during the addition. The triethylamine salt precipitates from solution. The reaction slurry is transferred to a 4.0 liter beaker, and with vigorous stirring there is added 3.0 liters of ice water to precipitate an oil. The oily product is dissolved in ether and separated from the water phase. The ether layer is washed two times with 300 ml. of water. After separation, anhydrous sodium sulfate is added to the ether layer to dry residual water from the product. The solution is filtred to remove the sodium sulfate and the ether is allowed to evaporate to give a dark brown solid. This material is recrystallized from alcohol to yield a white solid which melts at 7778 C. Analysis of the product shows 8.96% nitrogen and 21.14% sulfur. Calculated percentages for C H N OS are 9.30% nitrogen and 21.20% sulfur. The infrared spectrum is consistent with the proposed structure. The new imidazolidinones listed, supra, are prepared in as similar manner with comparable results.

To prepare N,N'-di(phenylthio)urea, a solution of 6.0 grams (0.1 mole) of urea and 25.0 grams (0.25 mole) of triethylamine in 200 m1. of DNF is cooled to C. in a three-necked 500 ml. flask equipped with a mechanical stirrer and thermometer. To this solution is added slowly 28.8 grams (0.2 mole) of benzene sulfenyl chloride dissolved in 77 ml. carbon tetrachloride. During the addition the temperature is allowed to increase to 5 C. and a slurry of the triethylamine salt forms. This slurry is transferred to a 4.0 litter beaker and the product is precipitated by the addition of 3.0 liters of ice water with vigorous stirring. The brown solid is collected by filtration and upon recrystallization from ethanol yields a tan powder which melts at 104-105 C. Analysis of the product shows 9.58% nitrogen and 23.13% sulfur. Calculated percentages for C H N OS are 9.60% nitrogen and 22.00% sulfur. The infrared spectrum is consistent with the proposed structure. The new ureas listed, supra, are prepared in a similar manner with comparable results.

N-(phenylthio)maleimide is prepared in the following manner: 14.4 grams of benzene sulfenyl chloride is added slowly at -20 C. to a mixture of 9.8 grams (0.1 mole) of maleimide and 20.0 grams (0.2 mole) of triethylamine dissolved in 200 ml. of dry benzene in a three-necked 500 ml. reaction fiask equipped with a mechanical stirrer and thermometer. The reaction mixture is allowed to stir until it reaches room temperature. This requires about minutes. The triethylamine salt is collected by filtration, and the cake is washed with ml. of benzene. The filtrate is evaporated under reduced pressure until the product starts to precipitate from solution. The slurry is transferred to a 4.0 liter beaker and 3.0 liters of heptane is added with vigorous stirring. This precipitates the remaining product which is collected by filtration and washed with cold heptane. The product is allowed to dry overnight at room temperature. There is obtained 12.0 grams of product which, upon recrystallization from ethanol, has a melting point of 81-82 C. The infrared spectrum is consistent with the proposed structure. The new maleimides listed, supra, are prepared in a similar manner with comparable results.

N-(phenylthio) 4 cyclohexene-l,Z-dicarboximide is prepared in the following manner: 14.4 grams (0.1 mole) of benzene sulfenyl chloride dissolved in 30.0 grams of carbon tetrachloride is added slowly to a mixture of 14.9 grams (0.1 mole) of 4 cyclohexene-1,2-dicarboximide and 12.0 grams (0.12 mole) of triethylamine in 250 ml. of benzene at 15 C. in a 500 m1. three-necked flask equipped with a stirrer and thermometer. The temperature iscontrolled at 15 C. with external cooling during the addition of the benzene sulfenyl chloride. The reaction is then allowed to warm to room temperature and the triethylamine salt is removed by filtration, washed with a small amount of benzene and 200 ml. of heptane is added to the filtrate to precipitate the product. The benzene and heptane are removed under reduced pressure. There is obtained 25.2 grams of a white solid which melts at 108 C. The product is recrystallized from carbon tetrachloride and has a melting point of 121122.5 C. Analysis shows 5.29% nitrogen and 11.69% sulfur. Calculated percentages for C H NO S are 5.42% nitrogen and 12.39% sulfur. The new 4-cyc1ohexene-1,2-dicarboximides listed, supra, are prepared in a similar manner with comparable results.

The new 5,5-dimethylhydantoins and 1,4,5,6,7,7-hexachlorobicyclo[2.2.1] hept-5-ene-2,3-dicarboximides listed, supra, are prepared in a similar manner to N-(phenylthio)-4-cyclohexene-1,2-dicarboximide with comparable results.

1,3-bis(phenylthio) 2 benzimidazolinone is prepared in the following manner: 28.8 grams (0.2 mole) of benzene sulfenyl chloride dissolved in 31.2 grams of CCL; is added in one portion to a well-stirred solution of 13.4 grams (0.1 mole) of 2-hydroxybenzimidazole dissolved in 250 ml. of DMF cooled to 0 C. The temperature is maintained between 0 to 5 C. by cooling with an external acetone/ice bath. To the resulting solution over a 15-minute period is added slowly 25.0 grams (0.25 mole) of triethylamine. Upon addition of all the amine, the resulting reddish slurry is transferred to a 4.0 liter beaker with vigorous stirring, and the reaction is quenched by the addition of 3.0 liters of ice water. The amine salt is dissolved and a thick viscous oil results. After decanting the water away from the oil layer, the latter solidifies to give a red solid. This material is recrystallized from ethyl acetate to yield 15.0 grams of a white solid, melting point 117 C. The infrared spectrum is consistent with the proposed structure. Analysis of the product shows 7.98% nitrogen and 18.12% sulfur. Calculated percentages for C H N OS are 7.98% nitrogen and 18.39% sulfur.

The reaction product of 2-hydroxybenzimidazole with the sulfenyl chloride from mixed thiocresols is prepared in the same manner as the 1,3-bis (phenylthio) 2 benzimidazolinone. The semisolid obtained is recrystallized from ethanol to give 15.0 grams of a cream solid which melts from 1l5.5125 C. The infrared spectrum is consistent with the proposed structure. Analysis of this product shows 6.94% nitrogen and 16.04% sulfur. Calculated percentages for C H N OS are 7.44% nitrogen and 16.97% sulfur. 1,3-bis(chloropheny1thio) 2 benzimidazolinone, 1,3 bis(benzylthio) 2 benzimidazolinone, 1,3 bis(nitrophenylthio) 2 benzimidazolinone, 1,3 bis(t-butylthio) 2 benzimidazolinone, and 1,3- bis(m-tolylthio)-2-benzimidazolinone are prepared in the same manner as the 1,3-bis(phenylthio)-2-benzimidazolinone described above.

N- (phenylthio bicyclo [2.2. 1] hept-5-ene-2,3 -dicarboximide is prepared in the following manner: To a mixture of 16.3 grams (0.1 mole) of the imide of bicyclo[2.2.1] hept-S-ene-Z,3-dicarboxylie anhydride and 11.1 grams (0.11 mole) of triethylamine in 300 m1. of benzene, there is added dropwise with stirring 0.105 mole of benzene sulfenyl chloride as a carbontetrachloride solution over a 30 minute period. The temperature of the mixture is maintained at 30 C. during the addition. The reaction mixture is stirred an additional 10 minutes after the sulfenyl chloride solution is added. The reaction mixture is filtered to remove triethylamine hydrochloride and the filtrate is added to 3.5 liters of chilled heptane. A white solid is obtained weighing 17.6 grams. A sample of the N-phenylthio bicyclo [2.2. 1] hept-S-ene-2,3-dicarb0ximide melts at 123125 C. Analysis shows 5.37% nitrogen and 11.09% sulfur. Calculated percentages for are 5.16% nitrogen and 11.80% sulfur. N-phenylthionaphthalimide, N-phenylthio-3,4,5,6-tetrachlorophthalimide, N-phenylthio-3,4,5,6-tetrabromophtha1imide, and similar compounds are prepared in a similar manner to N-(phenylthio)bicyclo [2.2.1] hept-5-ene-2,3-dicarboxi-mide with comparable results.

N,N' bis(phenylthio) 1,2,3,4-benzenetetracarboxylic- 1,2:4,5-diimide is prepared in the following manner: To a solution of 21.6 grams (9.1 mole) of pyromellitic bisdicarboximide and 22.2 grams (0.22 mole) of triethylamine in 300 ml. of dimethylfonnamide, there is added dropwise with stirring 0.21 mole of benzene sulfenyl chloride as a carbontetrachloride solution. The temperature is maintained at 20 to 30 C. Three liters of ice water is added to the resulting slurry to precipitate the product. The N,N'-bis(phenylthio)-1,2,4,5-benzenetetracarboxylic-1,2:4,5-diimide product is a yellow solid. A sample of the product melts at 260 C. Analysis of the product shows 6.05% nitrogen and 14.60% sulfur. Calculated percentages for C H N O S are 6.48% nitrogen and 14.82% sulfur. N,N-bis(ar-tolylthio)-l,2,4,5-benzenetetracarboxylic-1,2:4,5-diimide and similar compounds are prepared in a similar manner with comparable results.

N-(cyclohexylthio)glutarimide is prepared in the following manner: Twenty grams (0.177 mole) of glutarimide is added in one portion to a mixture of 24 grams (0.24 mole) of triethylamine and 200 ml. of dimethylformamide. To the resulting solution, 26.5 grams (0.177 mole) of cyclohexylsulfenyl chloride dissolved in 150 ml. of n-pentane is added dropwise over a 30 minute period. The temperature of the reaction increases from about 23 C. to 40 C. during the addition. The resulting slurry is stirred for an additional 30 minutes and then transferred to a 3.0 liter beaker. Two liters of cold water is then added to the slurry with vigorous stirring, and a light tan precipitate is formed. The solid is collected by filtration and allowed to dry at room temperature. The tan solid is recrystallized twice from heptane to yield long white needles which melt at 83-85 C. Analysis of die product shows 13.70% sulfur and 6.02% nitrogen. Calculated percentages for C H NO S are 14.13% sulfur and 6.16% nitrogen.

Other glutarimides and 3,3-dimethylglutarimide compounds of this invention are prepared in a similar manner with comparable results. Analysis of N-(cyclohexylthio)- 3,3-dimethylglutarimide shows 12.25% sulfur and 5.34% nitrogen. Calculated percentages for C H NO S are 12.57% sulfur and 5.5% nitrogen.

The following tables illustrate the invention in greater detail and the best mode for carrying it out, but are not to be construed as to narrow the scope of our invention. For all the rubber stocks tested and described, infra, as illustrative of the invention, Mooney scorch times at 121 C. and 135 C. are determined by means of a Mooney plastometer. The time in minutes (t required for the Mooney reading to rise five points above the minimum viscosity is recorded. Longer times are indicative of the activity of the inhibitor. Longer times on the Mooney Scorch Test are desirable because this indicates greater processing safety. Percentage increases in scorch delay are calculated by dividing the Mooney scorch time of the stock containing the premature vulcanization inhibitor by the Mooney scorch time of the control stock, multiplying by 100, and subtracting 100. These increases show the percentage improvement in scorch delay over the control stock which contains no inhibitor. Additionally, cure ratings are calculated from the time required to cure the stocks at 144 C., and in some cases 153 C. Curing characteristics are determined by means of the Monsanto Oscillating Disc Rheometer described by Decker, Wise, and Guerry in Rubber World, December 1962, page 68. From the Rheometer data, R.M.T. is the maximum torque in Rheometer units, t or t is the time in minutes for a rise of three or two Rheometer units, respectively, above the minimum reading and is the time required to obtain a torque 90% of the maximum.

The trademarks of some compounds used in the practice of this invention are Santocure MOR, Santofiex 77, Santocure NS, DPG, Thiofide, and Vultrol. Santocure MOR is the accelerator Z-(morpholinothio)benzothiazole. Santofiex 77 is the antidegradant N,N-bis(1,4-dimethylpentyl)-p-phenylenediamine. Santocure NS is the accelerator N-tert-butyl-Z-benzothiazolesulfenamide. DPG is an accelerator reported to be diphenylguanidine. Thiofide is an accelerator reported to be benzothiazyl disulfide. Vultrol is a vulcanization retarder reported to be N-nitrosodiphenylamine.

Table I illustrates the results of using N-(phenylthio) succinimide and N-(benzylthio)succiuimide as premature vulcanization inhibitors in stocks of natural rubber containing the antioxidant Santofiex 77 and the accelerator Santocure MOR. From the data of Table I it will be noted that N-(phenylthio)succinimide and N-(benzylthio) succinimide are quite active in the presence of the accelerator as premature vulcanization inhibitors. From the intermittent ozone test, there appears to be no effect on the ozone resistance of the vulcanizates containing the inhibitors.

TABLE I Stocks Natural rubber 100 100 100 High abrasion furnace black-.. 50 50 50 he oxide 5 5 5 Stearic acid 3 3 3 Hydrocarbon softener. 10 10 10 Sulfur 2. 5 2. 5 2. 5 Santofiex 77. 3 3 3 Santocure MOR 0. 5 0. 5 0. 5 N-(Phenylthio)succinimide 1. 0 N-(Benzylthio)succinimide 1. 0 Mooney Scorch at 121 0.:

t5 20. 8 44. 0 40. 6 hrs-5 4. 1 4. 6 4. 5 Percent increase in scorch delay 111 95 Shore A hardness 58 60 58 Modulus'300, p.s.l 1,900 1, 930 1, 930 Ultimate tensile strength, p. 3,600 3, 600 3, 600 Ultimate elongation, percent- 490 490 480 Rheometer at 144 0.:

t 7. 2 13. 3 14. 0 tag... 19. 0 26.2 6.8 It! 025 005 k2 173 173 .165 Intermittent ozone Hours 90% retention 16 13 15 Hours retention 31 30 32 1 k is a specific rate constant measured in 'recoprocal minutes. See Coran, 37 Rubber Chemistry and Technology 689 (1964).

2 For method see Decker & Wise, Rubber World, Apnl 1962, p. 66.

In Table II it is shown that N- (phenylthio)succinimide functions as an inhibitor in natural rubber with Santocure NS as well as it did with the accelerator Santocure MOR. It is also shown in Table II that 0.25 part per hundred N-(phenylthio) succinimide with Santocure NS has about the same vulcanization characteristics as 1.0 part per hundred of the well-known retarder Vultrol with Santocure MOR. It is shown that increasing concentrations of N- (phenylthio)succinimide with Santocure NS does not inhibit the rate of crosslink formation as measured by the specific rate constant k The parameter k is actually increased with increasing amounts of N-(phenylthio) succinimide in the presence of the phenylenediamine antidegradants. Stocks containing N-(phenylthio)succinimide and Santocure NS also show an excellent rate of cure after the onset of vulcanization.

The code for Table II is as follows. The stocks contain:

Twelve stocks were tested. The stocks include the following:

Santocure MOR plus Santofiex 77.

Santocure MOR plus Santofiex 77 plus Vultrol (1.0 part). Santocure NS plus Santofiex 77. Santofiex NS plus Santofiex 77 plus N (phenylthlo) succmimide (0.25 part). Santocure N S plus Santofiex 77 plus N-(phenylthio) succtnumde (0.5 part Santocure NS plus Santofiex 77 plus N-(phenylthio) succinirnide (1.0 part). Santocure MOR plus N-l, 3-dimethylbutyl-N-phenylp-pheuylenediamine. Santocure MOR plus N-l, 3-dimethylbutyl-N-phenylp-phenylenediamine plus Vultrol (1.0 part). Santocure NS plus N-l, 3-diruethylbutyl-N-phenyl-pphenylenediamine. Santocure NS plus N-1, 3-dimethylbutyLN-phenyl-ppiggylentediamine plus N-(phenylthio)succinimide par Santocure NS plus N-l, 3-dimethylbutyl-N-phenyl-pagenylegeeliamine plus N-(phenylthio)succinimide par Santocure NS plus N-l, 3-dimethylbutyl-N'phenyl-pplhgnylegediaminc plus N-(phenylthio)succinimide par TABLE II Stock 1 2 3 4 5 6 7 8 9 10 11 12 Mooney scorch at 121 0.:

t5 20.3 28.0 23.9 27.6 32.7 43.0 40.6 48.6 37.6 47.4 56.0 70.5 Percent increase in scorch delay. 38.0 11.0 37.0 80.0 20.0 26.0 9.0 88.0 Rheometer at 144 0 Results comparable to the natural rubber preparations of Table II are obtained using cis-4-polybutadiene, butyl rubber, ethylene-propylene terpolymers, polymers of 1,3- butadiene, for example, 1,3-butadiene itself and of iso- 1 prene and copolymers of 1,3-butadiene with other monomers, for example, styrene, acrylonitrile, isobutylene, and methyl methacrylate as the base stock and N-(phenylthio)succinimide and N-(benzylthio)succinimide as the inhibitor. For example, Table III shows the premature vulcanization inhibitor properties of N-(pheny1thio)succinimide in a styrene-butadiene rubber B-5 masterbatch. The compound is compared with Vultrol in several systems. The code for Table III is as follows. A B-5 masterbatch is composed of Parts Oil-extended styrene-butadiene rubber containing 37.5% highly aromatic oil 137.5 Intermediate super abrasion furnace black 68.5 Zinc oxide 3.0 Stearic acid 2.0

The stocks also contain:

Antidegradant N-l,3 dimethylbutyl- N-phenyl-p-phenylenediamine 3.0. Premature vulcanization inhibitor As indicated below.

N-(phenylthio)succinimide (0.5 part) plus Santocure NS. N -(phenylthio)suecinimide (1 part) plus Santocure NS. N-(phenylthio)succinimide (1 part) plus Santocure MO R Beaiz lothiasyl disulfide (1 part) plus diphenylguahidlne par N-(phenylthio)succinimide (1 part) plus benzothlazyl disulfide (1 part) plus diphenylguanidine (017 part).

with the 'v-ulcanizing agent dicumyl peroxide. The masterbatch for Table IV is composed of:

Parts Smoked sheets 100 High abrasion furnace black Zinc oxide 5 Stearic acid 3 Hydrocarbon softener 10 Total parts 168 TABLE IV Parts Masterbatch 168 168 N-l,3-dimethylbutyl-N -ph enyl-p-phenylenediamine 1.5 1.5 Dicumyl peroxide 2. 0 2. 0 N-(phenylthio) succinimlde- 1. 0 Mooney scorch at 135 0.:

4.9 7.7 Percent increase in scorch delay 57 Table V illustrates the excellent results obtained using N-(cyclohexylthio)phthalimide as a premature vulcanization inhibitor in stocks of natural rubber, oil-extended styrene-butadiene rubber and a natural rubber/cis-4-polybutadiene blend tread stock. The natural rubber tread stock is composed of the following:

Natural rubber tread stock The oil-extended styrene butadiene rubber tread stock is composed of the following:

TABLE III Stock 12345678910 Mooney Scorch at 135 0.:

z. 26.9 20.6 300 20.8 24.3 26.5 31.0 39.0 100 19.5 Percent increase in socroh ay 11.0 0 18.0 29.0 50.0 450 95.0 Rheometer at 153 0.:

vultr-ol the known inhibitor Shows a mere 11% Oil-extended styrene-butadiene rubber tread stock 5 crease in scorch delay with Santocure MOR and no Parts increased delay with Santocure NS. But the compound Oil-extended styrenebutadiene rubber 1712 137.0 of our invention, at the same concentrations, shows a Aromatic oil 1.5 45% increase in scorch delay with Santocure MOR and Intermediate super abrasion furnace carbon black 65.0 a 50% increase with Santocure NS in styrene-butadiene Zinc oxide 3.0 rubber. Stearic acid 1.0

Table IV shows the premature vulcanization inhibitor N-l,3-dimethylbutyl-N'-phenyl-pproperties of N-,(phenylthio)succinimide in natural rubphenylenedlamine 1 2.0 her when a peroxide vulcanizing agent is used. N-(phenyl- Santocure MOR 1.2 thio)succinimide shows a 57% increase in scorch delay Su fur 2.0

1'7 The natural rubber/cis-4-polybutadiene blend tread is composed of the following:

Natural rubber/polybutadiene blend tread stock All stocks contain three parts Santoflex 77, 0.5 part Santocure MOR, and 2.5 parts sulfur.

TABLE VII Parts A-e masterbatch 168 168 168 168 168 168 Natural rubber smoked sheets 75.0 g-pllljenyillfiiogs tuty p C 4 pQlyblltadle'm N,N-dl(phenylthlo)urea Aromatic 011 5.0 1,3d})is(phenylthio)-2-imldazoll- 110116 Zmc ox1de N-(phenylthlo)maleimlde 81263116 acid 2.0 1() Mootney scorch at 121 0.: 24

v 5 .5 47.7 28.1 Intermediate super abraslon furnace carbon black 45.0 Percent increase in Scorch delay 0 17' 0 N-l,3-d1methylbutyl-N -phenyl-p- Rheometer at 144 0.:

phenylenediamine 2.0 f8"; Santocure NS 0.65 34.2 Sulfur 1.75 15 TABLE V Comparable results are obtained when the accelerator Natural rubber tread Stock, part5 Santocure NS and the antidegradant N-1,3-dimethylbutyl- N'-phenyl-p-phenylenediamine or a mixture of this anti- N- c clohex lthlo hthalimlde 1.0 Mmie smfch t i81 3 20 degradant and Santofiex 77 are used. Table VIII shows 21.2 98. Percent increase inscmh delay 36M N (phenylth10)male1m1de as a scorch inhibitor 1n a B 5 Rheometer at 144 0.; masterbatch of styrene-butadrene rubber.

i 7.3 22.0 a: 2-3 s 162 .173 TABLE VIII ollextended styrene-butadiene tread stock, parts 4 EB N-(cyclohexylthio)phthallmlde 0.25 0.50 1.00 "1'; Mooney scorch at 135 0.: 3 9 42 6 5 7 70 4 i. 1: 0

v e Perct ant increase in scorch delay 38 74 128 'g fl ifffifi fi fi fifi fi fffffff i 2 2 2 2 Rheometer at 153 0.: 5 11 L7 7 1 7 1 7 2--- Mooney scorch at 135C 10.4 22.8 22.3 41.8 Percent increase in scorch de1ay. 119 83 3 2 6 5 Rheometer at 153 0.: J65 R.M.T 53.7 45.4 53.0 47.0 Natural rubber/polybutadiene blend tread stock, par s 25:11:: I: 3:; 3:3 $81? 53:3

1' N-(cyclohexylthio)phthalimlde 0.1 0.2 o 4 Mooney scogchz a5 1 55 a 68 4 86 0 eet lg ifimimsararessyjj::i:i-. 1 2 e; Table 1X illusgatgs 7 1:; useful prtemalturfe grucanizatio? tsatl 5- properties in an ru 1 er master atc o isopropya 87 142 Percent increase in 7 5 th1o)phthal1m1de and N-(n-butylth1o)psthal1rmde. The

TABLE VI Parts N-(benzylthlo) phthallmide 0. 25 0. 50 1. 00 Mooney scorch at 135 0.:

t 26 4 31. 7 34.6 38.3 Percent increase in scorch delay 20 35 45 N-(n-dodecylthlo)phthalim1de 0. 25 0. 1. 00 Mooney scorch at 135 0.:

t5 26. 4 28. 8 33. 9 38. 1 Percent increase in scorch delay 9 28 44 Table VII shows the results of tests on N-(phenylthio). succinimide, N-(t-butylthio)phthalirnide, N,N'-di(phenylthio)urea, 1,3-bis(phenylthio)-2-imidazolinone and N- (phenylthio)rnaleimide as premature vulcanization inhibitors in rubber. N-(phenylthio)malcimide gives a. 174% increase in scorch delay over the control. The rubber mixture of the test is an A-6 masterbatch. An A-6 masterbatch is composed of the following.

Parts Smoked sheets 100 High abrasion furnace black 50 Zinc oxide 5 Stearic acid 3 l0 Hydrocarbon softener Total parts 168 TABLE IX 0 ontrol N (isopropylthi0) phthallmlde N-(n-butylthio) phthalimide Mootney scorch at 0.:

In similar tests, N-(sec.-butylthio)phthalimide shows a 212% increase in scorch delay, and l,3-bis(n-dodecylthio)benzimidazolinone shows a 52% increase in scorch delay.

In an A-6 masterbatch containing 0.5 part Santocure MOR, 2.5 parts sulfur, and 3 parts Santoflex 77, the known compound, N-(phenylthio)phthalimide shows a 108% increase in scorch delay. N-(phenylthio)phthalimide is difficult to disperse in rubber probably due to its high melting point (163 -165 0.

Table X illustrates the properties of a mixture of ortho-, meta-, and para-N-(tolythio)phthalimide as a premature vulcanization inhibitor in an A-6 masterbatch using the antidegradants, Santoflex 77 and N-l,3-dimethylbutyl-N- phenyl-p-phenylenediamine. An 81% increase in scorch delay takes place with Santoflex 77 and a increase is noted with N-l,3-dimethylbutyl-N'-phenyl-p-phenyl enediamine. All stocks contain 0.5 part Santocure NS and 2.5 parts sulfur. Comparable results are obtained with other antidegradants.

1,3-bis(phenylthio)-2-benzimidazolinone is an excellent premature vulcanization inhibitor. In an A-1 masterbatch, this compound increased the scorch delay 170% as shown in Table XI.

An A-1 masterbatch is composed of:

Parts Natural rubber 100 High abrasion furnace black 50 Stearic acid 3 Zinc oxide 5 Hydrocarbon softener 3 Total parts 161 TABLE XI A-l masterbatch 161.0 161. Sulfur 2.0 2. 0 Santocure MO R. 0. 0.5 1,3-bis(phenylthio)-2-benzimldazollnone 1. 0 lS/imtoilex 77. 3. 0 3. 0

00118 SCOIC a t5 4. 3 65.8 Percent increase in sco 170. 0 Rheometer at 144 C R.M. 53. 7 n 17. 7 too 29. 5

Comparable results are obtained using the accelerator Santocure NS.

l,3-bis(phenylthi0) 2 benzimidazolinone, N-(phenylthio succinimide and 1,3-bis (trichlorornethylthio -2-benzimidazolinone are premature vulcanization inhibitors in cis-4-polybutadiene as shown in Table XII. 1,3-bis(pheny1 thio)-2-benzimidazolinone shows a 47% increase in scorch delay, N-(phenylthio)succinirnide shows a 31% increase, and 1,3-bis(trichloromethylthio)-2-benzimidazolinone shows 14% increase in cis-4-polybutadiene. The

masterbatch for Table XII is composed of:

Parts Cis-4-polybutadiene 100 Aromatic extender and process oil 8 Stearic acid 2 Santoflex 77 3 Xinc oxide 3 Intermediate super abrasion furnace black 50 TABLE XII Mastcrbatch 166 166 166 166 1,3-bis (tn'ehloromethylth1o)2-bcnzimldazolinone 1. 0 N-(phenylthio)sueclnim1de. 1. 0 1,3-bis(phenylthio)-2-benzim1dazollnon 1. 0 Santocure MOR 0.6 0. 6 0.6 Sulfur 2. 4 2. 4 2. 4 2. 4 Mooney scorch at 135 0.:

t5-.. 15. 5 17. 7 20. 3 22. 8 Percent increase in scorch delay 14 47 Itheometer at 153 C.:

R.M.I 58. 0 78. 0 61. 2 57. 2 t2 7.6 8.3 8. 6 9.8 ton 15. 7 19. 0 17. 5 18. 2

1,3 bis(phenylthio) 2 benzimidazolinone and N- (phenylthio)succinimide are premature vulcanization inhibitors in ethylene-propylene terpolymer as shown in Table XIII. Ethylene-propylene terpolymer is the recognized and commonly used name for the polymerized product from the polymerization of ethylene propylene and a small quantity of a nonconjugated diene. The terpolymer reported in Table XIII is known commercially as Nordel 1070. N-(phenylthio)succinimide shows a 28% increase in scorch delay and 1,3-bis(pl1cnylthi )-2-benzimidazo- 20 linone shows an increase when used as premature vulcanization inhibitors in ethylene-propylene terpolymer. The masterbatch of Table XIII is composed of:

Parts Ethylene-propylene terpolymer High abrasion furnace black 80 Zinc oxide 5 Naphthenic-type oil plasticizer and softener 40 TABLE XIII Master batch 225 225 225 Tetramethyl thiuram monosulfide 1. 5 1. 5 1. 5 Mercaptobenzothiazole 0.5 O. 5 0. 5 N-(phenylthio) succinimide 1. 0 1,3-bis(phenylthio)benzimidazolinone. 1. 0 Sulfur 1.5 1 5 1.5 Mooney scorch at C.

t. 10. 9 14. 9 20. 5 Percent increase in scorch delay 28 80 Rheometer at 0.:

1,3 bis(o-nitrophenylthio) 2 benzimidazolinone shows a 57% increase in scorch delay in an A-6 masterbatch. The results are in Table XIV.

Comparable results are obtained with the inhibitor 1,3 bis-(chlorophenylthio)-2-benzimidazolin0ne.

An ortho-, meta-, and para-mixture of 1,3-bis(tolylthio)- 2-benzimidazolinone gives a 163% increase in scorch de lay over the control, and 1,3-bis(m-tolylthio)-2-benzimidazolinone increases the delay 142%. These data are shown in Table XV.

TABLE XV A-6 masterbateh 168 168 168 Santofiex 77 3.0 3.0 3.0 Santocure MO R 0. 5 0. 5 0.5 u ur 2. 5 2. 5 2. 5 0,111 ,p-Mixture of 1 ,3-bis(tolylth1o) -2-bcnzimidazolinone 1. 0 1,3-bis(m-tolylthio)2-benzimidazolinone 1. 0 Mooney scorch at 121 C.:

22. 7 59. 8 54. 9 Percent increase in scorch delay 163.0 142. 0 Rheometer at 144 0.:

R 56. 9 56. 3 57. 0 tz---- 8.8 17.5 16.2 in 20. 2 29. 0 27. 5

The ortho-, meta-, and para-mixture of l,3-bis(tolythio)- Z benzimidazolinone was tested in a B-5 masterbatch of styrene-butadiene rubber. A 113% increase in scorch de- Iay over the control is obtained with an accelerator mixture of DPG and Thiofide and the inhibitor. The inhibitor gives an 80% increase in scorch delay when used with Santocure NS in styrene-butadiene rubber. These results are shown in Table XVI below.

TABLE XVI 13-5 masterbatchnv 211 211 211 211 Thiofide 1. 40 DP G 0. 7 Santoeure NS 1. 40 1. 40 N-1,3-dimethylbutyl-N-phcnyl-p-phenylenediamine 2. 0 2. O 2. 0 o,m,p-Mixture of 1,3 bis(t0ly1thio)-2-benzimidazollnone 1.0 1. 0 Sulfur 1. 7 1. 7 1. 7 1. 7 Mooney scorch at 135 C t;, 10.3 22 3 23. 3 41. 8 Percent increase in scorch delay 80 Rheometer at 153 C.:

R.M.T 46. 2 15. 3 27. 8

21 N-phenyl-N'-(phenylthio)urea was tested in an A6 masterbatch as a premature vulcanization inhibitor and shows a 97% increase in scorch delay over the control. The results are reported in Table XVII.

TABLE XVII A-S masterbatch 168 168 Sulfur 2. 5 2. 5 Santocure MOR. 0. 5 0. 5 Santofiex 77 3.0 3.0 N-phenyl-N (phenylthio)urea 1. Mooney scorch at 121 C.:

23. 46. 3 Percent increase in scorch delay 97 TABLE XVIII A1 masterbatch 161 161 161 Santocure MO R- 0.5 0.5 0.5 Sulfur 2. 5 2. 5 2. 5 1,4,5,6,7,7-hexachloro-N-(tr bieyclo[2.2.]-hept-5-ene-2,3-dicarboximide 1. 0

1,3-bis(t1ichloro1nethylthio)-5 6-dichlor0-2- benzimidazolinone 1. 0 Mooney scorch at 121 C 30. 5 53.0 51. 0 Percent increase in scorch delay 74. 0 67.0 Rheometer at 144 C.

R.M.T 70. 1 70.0 70.0 7. 9 12.0 12.2 23.0 39. 0 30.0

1,3-bis(trichloromethylthio) 5 chloro 2 benzimidazolinone shows a 49% increase in scorch delay in natural rubber.

Table XIX shows that N-[(trich1oromethy1)thio]- phthalimide is a premature vulcanization inhibitor for natural rubber using Santocure NS and Santocure MOR accelerators with and without the antidegradant Santoflex 77. A 25% increase in scorch delay takes place when N-[(trichloromethyl)thio]phthalimide and Santocure NS are tested with Santoflex 77, but without the antidegradant, a 9% scorch delay occurs. With Santocure MOR accelerator in the presence of Santofiex 77, a 57% increase in the scorch delay occurs. A higher modulus vulcanizate is obtained when this inhibitor is used with Santocure NS or Santocure MOR. Comparable results to those in Table XIX are obtained when the antidegradant N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine is used in place of Santofiex 77.

TAB LE XIX A-l Inasterbatch 161 161 161 161 161 161 161 Santocure NS 0. 5 0. 5 0.5 0. 5 Santocure MOR O. 0. 5 0. 5 Sulfur 2. 5 2. 5 2. 5 2 5 2. 5 2. 5 2. 5 N-[(trlchlororn hyl) phthalilnide 1. 0 1. 0 1.0 santoflex 77 3. 0 3. 0 3. 0 3. O Mooney scorch at 121 0.:

t 28. 3 31. 0 19. 5 24. 5 31.0 17. 3 27. 2 Percent increase in scorch delay 9 25 57 Rheometer at 144 0.:

R.M.T 74.0 76. 8 79. 8 74. 0 74. 5 77.4 10.0 7. 5 8.5 8. 7 5. 2 9. 6 37. 0 19. 5 21. 8 23. 0 17. 8 20. 0

Table XX shows that N-[(trichloromethyl)thio]succinimide is a premature vulcanization inhibitor. With Santocure NS accelerator in the presence of the antidegradant N-1,3 dimethylbutyl-N-phenyl-pphenylenediamine, this inhibitor improves the scorch delay about 43%. Comparable results are obtained when this antidegradant is replaced with Santofiex 77.

TABLE XX A-1 masterbatch. Santocure NS Santocure MO Sulfur N -[(trichloromethyl) thi succin'nnide 1. 0 1. 0 1. 0 N-l ,3 dimethylbuty1-N -phenyl-pphenylenediamine 3. 0 3. 0 Mooney scorch at 121 0 t5 28. 8 33.0 27 38. 5 32. 7 47 Percent increase in scorch delay 14 43 43 Rheometer at 144 0.:

Table XXI shows that the compounds 1,3-bis (trichloromethylthio) 2-benzimidazolinone, N-[(trichloromethyl) thio]-4-cyclohexene 1,2-dicarboximide, 5,5-dimethyl-3- [(trichloromethyl)thio]hydantoin, and N [(trichloromethyl)thio] maleimide are premature vulcanization inhibitors. In addition to the activity these compounds exhibit as premature vulcanization inhibitors, the rheometer tracings show that the rate of reversion during Overcure of natural rubber is reduced.

TABLE XXI A-l masterbatch Santoflex 77 Santocure MOR 5,5-dimethyl-3 [(tric hydantoin N-[(trichlorornethyl)thio]-maleimide 1,3-bis(trichloromethylthio)-2- benzimidazolinone 1. 0 Mooney scorch at 121 0.:

18. 3 30.8 34. 3 30.0 39. 4 Percent increase in scorch delay 68. 0 87. 0 64. 0 115. 0 Rheometer at 144 0.:

R.M.T 76. 5 79. 3 75. 5 82.5 t3 9. 0 10. 5 9.9 12. 6 18. 7 20. 6 23.0 23. 0

Parts Smoked Sheets Intermediate super abrasion furnace black 45 Zinc oxide 3 Stearic acid 2 Aromatic oil plasticizer 5 TABLE XXII Stock Masterbatch 155 155 Sulfur 2. 5 2. 5 2. 5 Santocure MOR 0. 5 0. 5 0. 5 N-1,3-dimethylbutyl-Nphenyl-p-phenylenediamine 2. 0 2. O 2. 0 N-(cyelohexylthio)glutarimide 1. 0 N -(phenylthio)benzamide l. 0 Mooney scorch at 121 0.:

5 35. 2 85. 8 85. 3 Percent increase in scorch delay 144 144 Rheometer at 144 0.:

R.M.T 61. 0 61. 2 63. 8

Table XXIV illustrates the use of 1,3-bis(cyclohexylthio) Z-imidazolidinone, 1,3-bis(cyclohexylthio)hydantoin, and 1cyclohexylthio-Z-imidazolidinone in a natural rubber masterbatch composed of the following:

Parts Natural rubber 100 Intermediate super abrasion furnace black 45 Stcaric acid 2.0 Hydrocarbon softener 5.0 Sulfur 2.5 Santocure MOR 0.5 Zinc oxide 3.0

TABLE XXIV Control 1 ,3-b is(cyclohexylthlo) 2-imidazo1rdinone. lcyclohexylth io-2-imidazolidinone 1,3-bis(cyclohexylthlo)hydantoin Mooney scorch at 121 0.:

t 23. 5 66. 3 58. 5 94. 9 Percent increase in scorch delay 182.0 149. 0 336.0 Rheometer at 144 0 R.T.M 58. 8 61. 5 57. 0 15. 0 15. 0 22. 0 35. 2 31. 8 38.0

Table XXV illustrates the use of 1,3-bis(p-chlorophenylthio)imidazolidinone in a natural rubber masterbatch containing the same ingredients as the masterbatch of Table V.

TABLE XXV Control r 7 1,3-bis(p-ehlorophenylthlo)imldazolldinone 1. 0 Mooney scorch at 121 0.:

t5 43. 3 96. 9 Percent increasein scorch delay 114. 0 Rheometer at 144 0.:

Table XXVI illustrates the use of 1-(n-dodecylthio)-2- imidazolidinone in an A-6 masterbatch containing 2 parts N-l,3-dimethylbutyl-N'-phenyl p phenylenediamine, 0.5 parts Santocure MOR, and 2.5 parts sulfur.

Table XXVII shows that comparable results are obtained when the imide moiety is benzimidazolinon-l-yl, benzothiaZolinon-l-yl, or benzoxaZolinon-l-yl, and that good results are obtained when the imide moiety is 5,5- diphenyl-3-hydantoinyl.

The control stock (1) is stock A of Table I, supra, to

24 which is added 1 part of prevulcanization inhibitor as follows:

Stock N o 1 None. 2 3-(trlchloromethylthio) -5,5-dlplienyl hydantoln. 3- S-tn'chloromethyl-2-benzothlazolinone. 4 l-trichloromethylthio2-benzlmidazolin0ne. 5 3trichloromethylthio-2-benzoxazollnonc.

The results for Stock No. l are the average values obtained from three separately prepared samples.

TABLE XXVII Stock Mooney scorch at 121 0 5 22.1 37.5 30.8 31.1 32.1 tan 3.4 3.8 2.3 3.7 2.6

The imide moiety may, of course, be formed from two independent radicals as in (A) NSR where A is acyl derived from a carboxylic acid and R is alkyl, cycloalkyl, or aryl. A is, for example,

it R0- where R is alkyl, cycloalkyl, or aryl. Similarly, SR may be the substituent of a simple amide as in A-fi-SR illustrated in Table XXII or two SR substituents may be present as in AN(SR) Table XXVIII shows the curing characteristics determined by means of the Rheometer with a stock containing AN-(SR) The control stock (1) is Stock A of Table I, supra, to which is added 1 part by weight of prevulcanization inhibitor as follows:

Stock Prevuleanization inhibitor 1 None.

TABLE XXVIII Stock Rheometer at 144 0.:

Comparable results to those in the tables, supra, illustrating utility are obtained with the inhibitors of this invention which are not illustrated.

Concentration studies show the inhibitors of this invention are efiective in rubber at concentrations of 0.05 to 5.50 parts per hundred. Concentrations from 0.10 to 3.0 parts per hundred are preferred.

A wide variety of combinations of Santocure NS and N-(phenylthio)succinimide show storage stability in an eight-Week oven aging test at 50 C. These combinations are improved vulcanization accelerators in rubber whereby premature vulcanization is effectively inhibited. Effective inhibitor concentrations for the combinations range from 1 to 9 parts of inhibitor. Comparable results are obtained when other accelerator and inhibitor combinations of this invention are tested for stability.

TABLE XXIX Assay, Assay, Decrease days 21 days in assay Santocure NS 99. 2 97. 6 1. 6 gantocure R 29. g 91. 6 7. 8.

an ocure 9.

N-(cyclohexylthio)phtha 49. a} 0 Santocure M0 R 46. 9} 47 0 None N-(cyclohexylthio)phthalimide. 50. 1

The data in Table XXIX illustrate that there is no decrease in assay for Santocure NS or Santocure MOR when these accelerators are used in the combinations of this invention. Decreases in assay in Santocure NS and Santocure MOR alone are illustrated in the table to be 1.6 for Santocure NS and 7.8 for Santocure MOR.

N-(cyclohexylthio)phthalimide is useful as a stabilizer for styrene-butadiene rubber which has gone through a coagulation step. The styrene-butadiene rubber used is known commercially as SBR-1502. The SBR is prepared for the stabilizer test by adjusting the temperature of 1000 grams of unstabilized SBR latex in a beaker to 45 -50 C. The latex contains about 20% rubber, 79% water, and 1% soap. The initial pH of the latex is about 10. To this is added 335 ml. of 12.5% NaCl solution. The stabilizer to be tested is added in an emulsified form and then 1000 ml. of dilute (0.2%) sulfuric acid is added at a fast-dropping rate during about 20 minutes. As the pH falls during the acid addition, coagulation starts at about pH 9.09.5 and continues throughout the acidification. The pH is final 1y adjusted with 2% sulfuric acid to between about 2 and 4. The mixture is filtered, and the SBR crumbs are Washed with water, then dried in a vacuum oven. The dried SBR crumbs are then milled to uniformity, sheeted out at about 0.008", and air and oven aged. The SBR containing N- (cyclohexylthio)phthalimide is compared to SBR containing the known stabilizer, tris (nonylphenyl)phosphite, and to a blank which is SBR with no stabilizer present. The Mooney viscosity of the three stocks is determined initially and after oven aging at 100 C. for 16, 30, and 48 hours. The results are recorded in Table XXX. The Mooney viscosity is the torque required to turn a rotor em bedded in the rubber sample after rotating 4 minutes. The Mooney Viscosity Test has the American Society for Testing and Materials Designation D-1646-63.

TABLE XXX.MOONEY VISCOSITY Aging time, hours *Parts per hundred. Comparable results to those in Table XXX are obtained in the other diene rubbers of this invention.

From the foregoing description, it will be appreciated that in the formula can be a radical derived by removal of hydrogen from an imide of a dicarboxylic acid. The term imide of a 26' dicarboxylic acid is used in a configurational sense to indicate two carbonyls joined to a single nitrogen, although more than one such configuration may be present in the same molecule. For example, the monoand diimides of "benzene tetracarboxylic acid are regarded in the present specification and claims as imides of dicarboxylic acids. The hydantoins, uracil, and parabanic acid also fall into the category of imides of dicarboxylic acid. The cyclic ureas, by which are meant monocarbonyl cyclic ureas as distinuished from cyclic ureas containing two carbonyls joined to a single nitrogen, present a configuration the reverse of imides of dicarboxylic acids in that only a single carbonyl is present and is joined to two nitrogen atoms. The preferred radicals conforming to RO1II are derived from azoles. By azoles are meant the general class of pentatomic he-terocyclic ring compounds whether or not unsaturation is present in the ring. Both the imides of dicarboxylic acids and cyclic ureas include pentatomic heterocyclic ring compounds. Other suitable radicals are derived from monocarbonyl azoles containing one nitrogen atom and one other diiferent hetero atom, for example, sulfur or oxygen, in the ring.

The radicals derived by removal of hydrogen from an imide of a dicarboxylic acid include, for example,

where A is a divalent aliphatic, cycloaliphatic, or aromatic radical. Thus, A is alkylene, cycloalkylene, alkenylene, cycloalkenylene, or arylene. Alkylene radicals belong to the series C H Alkenylene radicals are olefinical- 1y unsaturated aliphatic divalent radicals having the valence on separate carbon atoms, for example, propenylene -CH CH:CH. The corresponding cyclic forms are cycloalkylene, for example, cyclohexylene C H and cycloalkenylene, for example, cyclohexenylene C H The divalent aromatic radicals are arylene radicals, for example, phenylene. The radicals derived by removal of hydrogen from a monocarbonyl cyclic urea include, for example,

where A has the same meaning as before and X is hydrogen, alkyl, aryl, cycloalkyl, or SR", R" being alkyl, aryl, or cycloalkyl.

Suitable acyclic ureas may be represented by the formula where X, Y, and Z individually are hydrogen, R", or SR", R being alkyl, aryl, or cycloalkyl as before.

The special case wherein an imido radical is formed from two independent acyl radicals and amide derivatives comprise other valuable classes which may both be represented by the formula (RC)HN (SR)..'

where n, n, and n" are integers, the sum of which is three, n and n being one or two, and n" being zero or one,

and R and X having the same meaning as before.

It is intended to cover all changes and modifications the group consisting of the formulas:

-1'q-sR wherein is a radical derived by removal of hydrogen from a. imide of a dicarboxylic acid, from a monocarbonyl cyclic urea, from an imide in which the nitrogen is linked to carbonyl by alkylene, and from a monocarbonyl azole containing one other difierent hetero atom in the ring, and R is aryl, alkyl, or cycloalkyl,

Where X, Y, and Z individually are hydrogen, R, or SR, R having the same meaning as before, and

where n, n" and n" are integers, the sum of which is three, n and n being one or two, and n" being zero or one, and R and X having the same meaning as before.

2. The method according to claim 1 where the rubber also contains an organic vulcanization accelerating agent and where the compound to inhibit premature vulcanization is of Formula (a) wherein is a radical derived by removal of hydrogen from an imide of a dicarboxylic acid which radical has the formula where A is alkylene, cycloalkylene, arylene, alkenylene, or cycloalkenylene.

3. The method according to claim 1 where the rubber also contains an organic vulcanization accelerating agent and Where the compound to inhibit premature vulcanization is of Formula (a) wherein o o H II RSN\ N- o 0 H I] o 0 where R has the same meaning as in Formula (a).

4. The method according to claim 1 where the rubber also contains an organic vulcanization accelerating agent and where the compound to inhibit premature vulcanization is of Formula (a) where is a radical derived by removal of hydrogen from an imide of a dicarboxylic acid, which radical has the formula I? HN-C o Y I] where X and Y individually are hydrogen, alkyl, aryl, or cycloalkyl.

5. The method according to claim 1 where the rubber also contains an organic vulcanization accelerating agent and where the compound ot inhibit premature vulcanization is of Formula (a) wherein R is cycloalkyl and X and Y individually being hydrogen, alkyl, aryl or cycloalkyl, and where R has the same meaning as before.

6. The method according to claim 1 where the rubber also contains an organic vulcanization accelerating agent and where the compound to inhibit premature vulcanization is of formula (a) wherein 0 II ,0 t I is a radical derived by removal of hydrogen from a monocarbonyl cyclic urea which radical has the formula Where A is alkylene, cycloalkylene, arylene, alkenylene, or cycloalkenylene, and X is hydrogen, R, or SR, R having the same meaning as in formula (a).

7. The method according to claim 1 Where the rubber also contains an organic vulcanization accelerating agent and Where the compound to inhibit premature vulcanization is of formula (a) wherein is a radical derived by removal of hydrogen from a monocarbonyl azole which radical has the formula wherein A is arylene and X is oxygen or sulfur.

8. The method according to claim 1 Where the rub her also contains an organic vulcanization accelerating agent and where the compound to inhibit premature vulcanization is of formula (b).

9. The method according to claim 8 wherein Y and Z are hydrogen and X is SR.

10. The method according to claim 1 where the rubber also contains an organic vulcanization accelerating agent and where the compound to inhibit premature vulcanization is of formula (c).

11. The method according to claim 10 where n, n, and n" are one and X is hydrogen.

12. The method according to claim 10 wherein n is one, n is two, and n" is zero.

13. The method according to claim 10 where H SEC- is benzoyl and n is one.

14. The method of inhibiting premature vulcanization of a sulfur vulcanizable diene rubber containing a vul canizing agent and an organic vulcanization accelerating agent, which comprises:

incorporating therein, in an amount effective to inhibit premature vulcanization, a compound of the formula RS-R where R' is an imido radical and R is alkyl, aryl, or cycloalkyl.

15. Diene rubber vulcanizable compositions having improved resistance to premature vulcanization comprising vulcanizable diene rubber containing a sulfur vulcanizing agent, an organic vulcanization accelerating agent and in amount eifective to inhibit premature vulcanization, a compound of the formula RSR where R is an imido radical and R is alkyl, aryl, or cycloalkyl.

16. The method of inhibiting premature vulcanization of a sulfur vulcanizable diene rubber containing a vulcanizing agent and an organic vulcanization accelerating agent which comprises:

incorporating therein in an amount efiective to inhibit premature vulcanization a compound selected from the group consisting of the formulas wherein R and R with the carbonyl and N atom are N-phthalimidyl, N succinimidyl, 1,4,5,6,7,7 hexachlorobicyclo[2.2.1]hept--ene 2,3 dicarboximid- N yl, hydantoinyl, 5,5-dimethyl-3-hydantoinyl, 5,5- diphenyl-3-hydantoinyl, N-maleimidyl, N-adipimidyl, N-glutarimidyl, N-3,3-dimethylglutarimidyl, N-hexahydro-phthalimidyl, 7-oxabicyclo[3.2.2]heptane 2,3- dicarboximid-N-yl, 7 oxabicyclo[2.2.1]hept S-ene- 2,3 dicarboximid-N-yl, tetrapropenylsuccinimid-N- yl, methylsuccim'mid-N-yl, octadecylsuccinimid-N-yl, n-decenylsuccinimid N-yl, 4-cyclohexene-l,2-dicarboximid-N-yl, Z-benzimidazolinon-l-yl, 3-arylthio-2- benzimidazolinon-l-yl, 3-alkylthio-2-benzimidazolinon l-yl, 3-cycloalkylthio 2-benzimidazolinon-1-yl, 2-imidazolidinon 1-y1, 3-ary1thio-2-imidazolidinon- 1-yl, 3-alky1thio 2 imidazolidinon l-yl, 3-cycloalkylthio 2 imidazolidinon l-yl, Z-imidazolinon- 1-yl, 3 arylthio 2 imidazolinon l-yl, 3-alkylthio Z-imidazolinon l-yl, 3-cycloalkylthio 2-imidazolinon l-yl, bicyclo[2.2.1]hept 5 ene 2,3- dicarboximid-N-yl, alkylbicyclo[2.2.1]hept.-5-ene-2, 3-dicarboximid-N -yl, N-(arylthio) 1,2,4,5 benzene- 30 tetracarboxylic 1,2:4,5 diimid N'-yl, N-(cycloalkylthio) 1,2,4,5 benzenetetracarboxylic 1,224,5- diimid N'-yl, N-(alkylthio) 1,2,4,S-benzenetetra carboxylic 1,224,5-diimid N'-yl, N-naphthalimidyl, or N-(3,4,5,6-tetrahalophthalimidyl, and R" is aryl, cycloalkyl, or alkyl and wherein wherein R and R with the carbonyl and N atom are N-phthalimidyl, N succinimidyl, 1,4,5,6,7,7 hexachlorobicyclo[2.2.1]hept-5-ene 2,3 dicarboximid- N yl, hydantoinyl, 1-cyclohexylthio-3-hydantoinyl, 5,5 dimethyl-3-hydantoinyl, 5,5-diphenyl-3-hydantoinyl, N-maleimidyl, N-adipimidyl, N-glutarimidyl, N-3,3-dimethylglutarimidyl, N-hexahydro-phthalimidyl, 7-oxabicyc1o[2.2.1.]heptane-2,3 dicarboximid- N yl, 7 oxabicyclo[2.2.l]hept-5-ene-2,3-dicarboximid-N-yl, tetrapropenylsuccinimid-N-yl, methylsuccinimid-N-yl, octadecylsuccinimid-N-yl, n decenylsuccinimid N-yl, 4-cyclohexene-l,2-dicarboximid-N- yl, 2-benzimidazolinon-1-yl, 3-arylthio-2-benzimidazolinon-l-yl, 3-alkylthio-2-benzimidaz0linon-l-yl, 3- cycloalkylthioQ-benzimidazolinon-1 yl, 2-imidazo lidinon 1 yl, 3-arylthio 2 imidazolinon 1 yl, 3-alkylthio 2 imidazolinon-l-yl, 3-cycloalkylthio- 2 imidazolidinon-l-yl, bicyclo [2.2.1]hept-5-ene'-2,3- dicarboximid-N-yl, alkyl-bicyclo[2.2.1]hept 5 ene- 2,3-dicarboximid N yl, N- (arylthio) 1,2,4,5- *benzenetetracarboxylic-1,2:4,5 diimid N yl, N- (cycloalkylthio) 1,2,4,5 benzenetetracarboxylic- 1,2:4,5 diimid N-yl, N (alky1thio)-1,2,4,5-benzenetetracarboxylic 1,2:4,5 diimid N yl, N- naphthalimidyl or N-(3,4,5,6 tetrahalophthalimidyl, and

R is aryl, cycloalkyl, or alkyl and is N-(arylthio)carbamoyl, N-(alkylthio)carbamoyl, N (cycloalkylthio)carbamoyl, N arylcarbamoyl, N alkylcarbamoyl, or N-cycloalkylcarbamoyl, and

R is alkyl, cycloalkyl, or aryl.

18. The method of inhibiting premature vulcanization of a sulfur vulcanizable diene rubber containing a vulcanizing agent and an organic vulcanization accelerating agent which comprises:

incorporating therein in an amount effective to inhibit tains an amine antidegradant selected from the group con sisting of N,N-bis(1,4-dimethylpentyl) pphenylenediamine, N 1,3-dimethylbutyl-N'-phenyl p phenylenediamine, and mixtures thereof.

23. Diene rubber vulcanizable compositions having improved resistance to premature vulcanization according to claim 19 wherein the mii'tture contains an amine antidegradant selected from the group consisting of N,N-bis (1,4 dimethylpentyl)-p-phenylenediamine, N 1,3 dimethylbutyl-N'-phenyl-p-phenylenediamine, and mixtures thereof.

24. The method of inhibiting premature vulcanization of rubber according to claim 21 wherein the accelerator is 2- (morpholinothio benzothiazole.

25. The method of inhibiting premature vulcanization of rubber according to claim 21 wherein the accelerator is N-tert-butyl-2-benzothiazolesulfenamide.

26. The method of inhibiting premature vulcanization of rubber according to claim 21 wherein the accelerator is mercaptobenzothiazole.

27. The method of inhibiting premature vulcanization of rubber according to claim 21 wherein the accelerator is benzothiazyl disulfide.

28. The method of inhibiting premature vulcanization of rubber according to claim 18 wherein the inhibitor is N-(phenylthio)succinimide.

29. The method of inhibiting premature vulcanization of rubber according to claim 18 wherein the inhibitor is 1,3-bis- (phenylthio -2-benzimidazolinone.

30. The method of inhibiting premature vulcanization of rubber according to claim 18 wherein the inhibitor is N,N-di(phenylthio)urea.

31. The method of inhibiting premature vulcanization of rubber according to claim 18 wherein the inhibitor is N-(phenylthio)maleimide.

32. The method of inhibiting premature vulcanization of rubber according to claim 18 wherein the inhibitor is N- (tolylthio phthalimide.

33. The method of inhibiting premature vulcanization of rubber according to claim 18 wherein the inhibitor is N- (cyclohexylthio phthalimide.

34. Diene rubber vulcanizable compositions having improved resistance to premature vulcanization according to claim 19 wherein the inhibitor is N-(cyclohexylthio) phthalimide.

35. The method of inhibiting premature vulcanization of rubber according to claim 18 wherein the inhibitor is N- (cyclohexylthio succinimide.

36. The method of inhibiting premature vulcanization of rubber according to claim 18 wherein the inhibitor is N- (isopropylthio phthalimide.

37. The method of inhibiting premature vulcanization of rubber according to claim 18 wherein the inhibitor is N- n-butylthio phthalimide.

38. The method of inhibiting premature vulcanization of rubber according to claim 18 wherein the inhibitor is N-(n-dodecylthio)phthalimide.

39. The method of inhibiting premature vulcanization of vulcanizable diene rubber according to claim 16 including the following additional element:

heating the mixture.

40. The method of inhibiting premature vulcanization of a vulcanizable diene rubber according to claim 18 including the following additional element:

heating the mixture at a vulcanizing temperature.

41. An accelerator-inhibitor combination comprised of an organic vulcanization accelerating agent and a compound, in an amount effective to inhibit premature vulcanization of a vulcanizable diene rubber, selected from a group consisting of the formulas:

wherein o it 4' l is a radical derived by removal of hydrogen from an imide of a dicarboxylic acid, from an imide in which the nitrogen is linked to carbonyl by alkylene, from a monocarbonyl cyclic urea, and from a monocarbonyl azole containing one other different hetero atom in the ring, and R is aryl, alkyl, or cycloalkyl,

Y [I z XNC-N s n where X, Y, and Z individually are hydrogen, R, or SR, R having the same meaning as before, and

(Ro)..N(sR)..

where n, n, and n are integers, the sum of which is three, n and n being one or two, and n being zero or one, and R and X having the same meaning as before.

42. An accelerator-inhibitor combination comprised of an organic vulcanization accelerating agent and a compound, in an amount effective to inhibit premature vulcanization of a vulcanizable diene rubber, selected from the group consisting of the formulas:

wherein R and R with the carbonyl and N atom are N- phthalimidyl, N succinimidyl, 1,4,5,6,7,7 hexachlorobicyclo[2.2.1]hept-5-ene-2,3-dicarboximid N yl, hydantoinyl, 1-cyclohexylthio-3-hydantoinyl, 5,5 dimethyl 3 hydantoinyl, 5,5 diphenyl 3 hydantoinyl, N-maleimidyl, N-adipimidyl, N-glutarimidyl, N-3,3-dimethylglutarimidyl, N hexahydrophthalimidyl, 7 oxabicyclo[2.2.l]heptane 2,3 dicarboxirnid N yl, 7 oxabicyclo [2.2.1]hept-5-ene- 2,3-dicarboximid-N-yl, tetrapropenylsuccinimid I- yl, methylsuccinimid-N-yl, octadecylsuccinimid-N-yl, n-decenylsuccinimid N yl, 4-cyclohexene-1,2-dicarboXimid-N-yl, Z-benzimidazolinon 1 yl, 3-chlorophenylthio-2-benzimidazolinon 1 yl, 3-phenylthio-Z-benzimidazolinon-l-yl, 3-benzylthio-2-benzimidazolinon-l-yl, 3 nitrophenylthio-2-benzimidazolinon-l-yl, 3 cycloalkylthio 2 benzimidazolinonl-yl, 3-alkylthio-2-benzimidazolinon 1 yl, 3-to1ylthio-2-benzimidazolinon-l-yl, 2 imidazolidinon 1- yl, 3 phenylthio-2-imidazolidinon-l-yl, 3 chlorophenylthio-Z-imidazolidinon-1-yl, 3 benzylthio 2- imidazolidinon-l-yl, 3-tolylthio 2 imidazolidinonl-yl, 3-cycloalkylthio-2-imidazolidinon 1 yl, 3- alkylthio-Z-imidazolidinon-l-yl, Z-imidazolinon-l-yl, 3 phenylthio-2-imidazolinon-l-yl, 3 chlorophenylthio-2-imidazolinon-1-yl, 3 benzylthio 2 imidazolinon-l-yl, 3-tolylthio-2-imidazolinon-l-yl, 3 alkylthio-2-imidazolinon-l-yl, 3-cycloalkylthio-2-imidazo linonl-yl, bicyclo[2.2.1]hept-S-ene-Z,3-dicarboximid- N-yl, alkylbicyclo[2.2.l]hept 5 ene 2,3 dicarboximid-N-yl, N-(phenylthio) l,2,4,5 benzenetetracarboXylic-1,2:4,5-diimid-N'-yl, N (benzylthio)-1,2, 4,S-benzenetetracarboxylic 1,2:4,5 diirnid N-yl, N (chlorophenylthio) 1,2,4,5 benezenetetracarboxylic-l,2:4,5-diimid-N'-yl, N (nitrophenylthio)- l,2,4,S-benezenetetracarboxylic 1,2:4,5 diimid-N- yl, N-(alkylthio)-l,2,4,5 benezenetetracarboxylicl,2:4,5-diimid-N-yl, N-(cycloalkylthio) 1,2,4,5-benzenetetracarboxylic-1,2:4,5-diimid-N'-yl, N (tolylthio)-1,2,,4,5 benzenetetracarboxylic 1,2:4,5 di imid-N'-yl, N-naphthalimidyl, or N-(3,4,5,6 tetrahalophthalimidyl), and

35 R" is phenyl, benzyl, chlorophenyl, nitrophenyl, tolyl,

cycloalkyl, primary alkyl, or secondary alkyl and is N-(pheny1thio)carbamoyl, N-(chlorophenylthio) carbamoyl, N-(benzylthio)carbamoyl, N-(tolylthio) carbamoyl, N-(alkylthio)carbamoyl, N-(cycloalkylthio) carbamoyl, N-phenylcarbamoyl, N-alkylcarbamoyl, Ncycloalkylcarbamoyl, N-benzylcarbamoyl, N- nitrophenylcarbamoyl, N-chlorophenylcarbamoyl, or N-tolylcarbamoyl, and

R is phenyl, benzyl, chlorophenyl, nitrophenyl, tolyl,

primary alkyl, secondary alkyl, or cycloalkyl.

43. An accelerator-inhibitor combination according to claim 42 wherein the accelerator is a sulfenamide accelerator and the inhibitor is N- (phenylthio)succinimide.

44. An accelerator-inhibitor combination according to claim 42 wherein the inhibitor is N-(cyclohexylthio) phthalimide.

45. An accelerator-inhibitor combination according to claim 42 wherein the accelerator is a sulfenamide accelerator and the inhibitor is N- (cyclohexylthio)phthalimide.

46. An accelerator-inhibitor combination according to claim 42 wherein the accelerator is N-tertbutyl-2-benzo thiazolesulfenamide and the inhibitor is N-(cyclohexylthio)phthalimide.

47. An accelerator-inhibitor combination according to claim 42 wherein the accelerator is 2-(morpholinothio) benzothiazole and the inhibitor is N-(cyclohexylthio) phthalimide.

48. An accelerator-inhibitor combination according to claim 42 wherein the accelerator is a sulfenamide accelerator and the inhibitor is N-(cyclohexylthio)succinimide.

49. An accelerator-inhibitor combination according to claim 42 wherein the accelerator is a sulfenamide accelerator and the inhibitor is N-(n-butylthio)phthalimide.

50. Diene rubber having incorporated therein a compound selected from the group consisting of the formulas:

is a radical derived by removal of hydrogen from a imide of a dicarboxylic acid, from an imide in which the nitrogen is linked to carbonyl by alkylene, from a monocarbonyl cyclic urea, and from a monocarbonyl azole containing one other difierent hetero atom in the ring, and R is aryl, hydrocarbon alkyl, or cyaloalkyl,

where X, Y, and Z individually are hydrogen, R, or SR, R having the same meaning as before, and E O Qn I (R )nN( where n, n, and n" are integers, the sum of which is three, n and n being one or two, and n" being zero or one, and R and X having the same meaning as before.

51. A composition according to claim 50 wherein the rubber is a synthetic rubber which contains about 0.1 to about 5 parts of a compound of claim 50.

52. A styrene-butadiene rubber composition according 36 to claim 50 containing about 1.25 parts N-(cyclohexylthio)phthalimide per hundred parts of rubber.

53. Diene rubber having incorporated therein a compound selected from the group consisting of the formulas:

wherein R and R with the carbonyl and N atom are N- phthalimidyl, N-succinimidyl, 1,4,5,6,7,7-hexachlorobicyclo[2.2.l1hept 5 cue-2,3-dicarboXimid-N-yl, hydantoinyl, 1 cyclohexylthio 2 hydantoinyl, 5,5- dimethyl-3-hydantoinyl, 5,5-diphenyl S-hydantoinyl, N-maleimidyl, N-adipimidyl, N-glutarimidyl, N-3,3- dimethylglutarimidyl, N hexahydro phthalimidyl, 7-oxabicyclo[2.2.l]heptane-2,3-dicarboximid N yl, 7-oxabicyclo[2.2.1]hept 5 ene 2,3-dicarboximid- N-yl, tetrapropenylsuccinimid N yl, methylsuccinimid N yl, octadecylsuccinimid-N-yl, n-decenylsuccinimid-N-yl, 4 cyclohexene-l,2-dicarboXimid-N- yl, 2-benzimidazolinon 1 yl, 3-arylthio-2-benzimidazolinon-l-yl, 3-alkylthio 2 benzimidazolinon 1- yl, 3-cycloalkylthio 2 benzimidazolinon-l-yl, 2- imidazolidinon 1 yl, 3-arylthio-2-imidazolidinon-lyl, 3-a1kylthio 2 imidazolidinon-l-yl, 3-cycloalkylthio 2 imidazolidinon-l-yl, 2-imidazolinon-1-yl, 3- arylthio 2-imidazolinon-l-yl, 3-alky1thio-2-imidazolinon-l-yl, 3-cycloalkylthio 2 imidazolinon-l-yl, bicyclo[2.2.l]hept 5-ene-2,3-dicarboXimid-N-yl, alkylbicyclo[2.2.11hept 5 ene-2,3-dicarboximid-N-yl, N- (arylthio)-1,2,4,5 benzenetetracarboxylic-1,2:4,5-diimid-N'-yl, N-(cycloalkylthio) 1,2,4,5 benzenetetracarboxylic l,2:4,5-diimid-N'-yl, N-(alkylthio)- 1,2,4,5 benzenetetracarboxylic-1,2:4,5-diimid-N'-yl, N-naphthalimidyl, or N-(3,4,5,6-tetrahalophthalimidyl), and

R is aryl, cycloalkyl, or alkyl hydrocarbon, and

is N-(arylthio)carbamoyl, N-(alkylthio)carbamoyl, N-(cycloalkylthio)carbamoyl, N-arylcarbamoyl, N- alkylcarbamoyl, or N-cycloalkylcarbamoyl, and

R is alkyl hydrocarbon, cycloalkyl, or aryl.

54. A composition according to claim 53 wherein the rubber is a synthetic rubber which contains about 0.1 to about 5 parts of a compound of claim 53.

55. A styrene-butadiene rubber composition according to claim 54 containing about 0.5 to 3.0 parts N-(cyclohexylthio)-phtha1imide per hundred parts of rubber.

56. A stabilized thiazole sulfenamide composition for rubber compounding comprising a thiazole sulfenamide accelerator and a stabilizing amount of a compound selected from the group consisting of the formulas:

wherein is a radical derived by removal of hydrogen from an imide of a dicarboxylic acid, from an imide in which the nitrogen cyclic urea, and from a monocarbonyl azole containing one other different hetero atom in the ring, and R is aryl, hydrocarbon alkyl, or cycloalkyl,

Y II Z XNCNS R where X, Y, and Z individually are hydrogen, R, or SR, R having the same meaning as before, and

( O (X) n (R C) uN( S R) n where n, n, and n" are integers, the sum of which is three, n and n being one or two, and n" being zero or one, and R and X having the same meaning as before.

57. A stabilized thiazole sulfenamide composition for rubber compounding comprising a thiazole sulfenamide accelerator and a stabilizing amount of a compound selected from the group consisting of the formulas:

wherein R and R with the carbonyl and N atom are N- phthalimidyl, N-succinimidyl, 1,4,5,6,7,7-hexachlorobicyc1o[2.2.1]-hept ene-2,3-dicarboximid-N-yl, hydantoinyl, l-cyclohexylthio 3 hydantoinyl, 5,5- dimethyl 3 hydantoinyl, 5,5-diphenyl-3-hydantoinyl, N-maleimidyl, N-adipimidyl, N-glutarimidyl, N- 3,3-dimethylglutarimidyl, N-hexahydro-phthalimidyl, 7-oxabicyclo[2.2.1]heptane 2,3 dicarboXimid-N- yl, 7-oxabicyclo[2.2.1]hept 5 ene 2,3 dicarboXimid-N-yl, tetrapropenylsuccinimid N yl, methylsuccim'mid-N-yl, octadecylsuccinimid-N-yl, n-decenylsuccinimid-N-yl, 4 cyclohexene 1,2 dicarboximid-n-yl, 2-benzimidazolinon-l-yl, 3-chlorophenylthio 2 benzimidazolinin 1 yl, 3-phenylthio-2- benzimidazolinon 1 yl, 3-benzylthio 2-benzimidazolinon-l-yl, 3 nitrophenylthio-2-benzimidazolinonl-yl, 3-cycloalkylthio 2 benzimidazolinon-l-yl, 3- alkylthio 2 benzimidazolinon-l-yl, 3-toly1thio-2- benzimidazolinon 1 yl, 2 -imidazolidinon-1-yl, 3- phenylthio-Zdmidazolidinon 1 yl, 3-chlorophenylthio-2-imidazolidinon 1 yl, 3-benzylthio-2-imidazolidinon-l-yl, 3-tolylthio 2 imidazolidinon-l-yl, 3-cycloalkylthio 2 imidazolidinon-l-yl, 3-alkylthio- 2-imidazolidinon-1-yl, Z-imidazolinon-l-yl, 3-pheny1- thio-2-imidazolinon 1 yl, 3-chlorophenylthio-2- imidazolinon-l-yl, 3 benzylthio 2 imidazolinonl-yl, 3 tolylthio 2 imidazolinon-l-yl, 3-alkylthio- 2-imidazo1inon-1-yl, 3-cycloalkylthio-2-imidazolinonl-yl, bicyclo[2.2.1]hept 5 ene2,3-dicarboximid- N-yl, alkylbicyclo[2.2.1]hept 5 ene-2,3 dicarboximid-N yl, N (phenylthio) 1,2,4,5 benzenetetra- 38 carboxylic-1,2:4,5-diimid-N'-yl, N (benzylthio)- 1,2,4,5 benzenetetracarboxylic 1,2:4,5 diimid-N- yl, N (chlorophenylthio)-1,2,4,5 benzenetetracarboxylic 1,2:4,5 diimid-N'-yl, N-(nitrophenylthio)- 1,2,4,5 benzenetetracarboxylic 1,2:4,5 diimid-N'- yl, N-(alkylthio) 1,2,4,5 benzenetetracarboxylic- 1,2:4,5 diimid-N'-yl, N-(cycloalkylthio) 1,2,4,5- benzenetetracarboxylic 1,2:4,5 diimid-N'-yl, N- (tolylthio)-1,2,4,5 benzenetetracarboxylic 1,2:4,5- diimid N yl, N-naphthalimidyl, or N-(3,4,5,6- tetrahalophthalimidyl) and R" is phenyl, benzyl, chlorophenyl, nitrophenyl, tolyl,

cycloalkyl, primary alkyl, or secondary alkyl and R t r'r s R wherein is N-(phenylthio)carbamoyl, N-(chlorophenylthio) carbamoyl N-(benzylthio)carbamoy1, N-(tolylthio) carbamoyl, N alkylthio)carbarnoyl, N (cycloalkylthio)carbamoyl, N-phenylcarbamoyl, N alkylcarbamoyl, N-cycloalkylcarbamoyl, N benzylcarbamoyl, N nitrophenylcarbamoyl, N chlorophenylcarbamoyl, or N-tolylcarbamoyl, and

R is phenyl, benzyl, chlorophenyl, nitrophenyl, tolyl,

primary alkyl, secondary alkyl, or cycloalkyl. 58. A composition of claim 56 where the accelerator is N-tert-butyl-2-benzothiazolesulfenamide and the stabilizer is N- (cyclohexylthio phthalimide.

59. The method according to claim 1 wherein R is tri- JOSEPH L. SCHOFER, Primary Examiner C. A. HENDERSON, JR., Assistant Examiner U.S. Cl. X.R.

Ivmmm (J) Aubert Yaucher Coran and Joseph Edward Kerwood 1.1: 1'1; CCTtiFfH'd liiml. (11'1"01" (appoints in the rdlc-vvidcntificd patent. and tlmt. staid Lctluvu Patent are hczrvhy corrected as shown below:

Add to the Title: "With Sulfenamide Characterized by Carbonyl Adjacent to the Sulfenamide Nitrogen Column 1, line 26, after "cycloalkyl" and before the period, insert -are used to inhibit premature vulcanization of Nulcanizable elastomers and to stabilize thiazole sulfenamide accelerat0rs--.

Column 9 line 50, "amide" should read "amine" Column 10, line 25, "compound should read "compounds" Column 10, line 29, "pasesd" should read "passed" Column 11, line 10, "litter" should read "liter.

Column 14, Table I, Stock C opposite t which reads "6. 8" shot read "26 8" Column 14, line 23, "recoproca l" should read "reciprocal" Column 14, line 63, stock no. 4, "Santoflex" should read "Santocure" Column l5; line 50, "di'phenylguahidine" should read "diphenylguanidine".

" Column 15, line 53, second line of stock no. 10, "017 part" should read "0.7 part".

Column 18 line 40, "psthalimide" should read "phthalimide" (Page 1 of 2) 

